The present invention relates to a battery for feeding power to, e.g., a communication apparatus located outside of a station building or inside of an unmanned station building.
A communication apparatus installed in a station building has customarily been fed by a power source available in the building or by a back-up battery. The battery installed in the building does not need a waterproof or similar specific implementation. In addition, hydrogen gas output from the battery is driven out of the building by, e.g., a fan.
A current trend is, however, toward a small size station building or a casings to be mounted on a pole due to the increasing ground rent, extending transmission distance, and expanding subscriber services. While such a building or casing usually receives power from an electric cables in order to feed a communication apparatus, it is loaded with a battery in case of power failure. Because the battery itself is situated outdoors, the casing is provided with a waterproof structure. The casing must be provided with a vent hole for venting hydrogen gas output from the battery. The vent hole may be formed in the bottom of the casing. However, the problem is that the vent hole admit dust and insects into the casing.